S. Johansson, Origins of language (rozdział 10).pdf

Origins of Language

Constraints on hypotheses

Sverker Johansson

University of Jönköping

John Benjamins Publishing Company

Amsterdam

Philadelphia

The paper used in this publication meets the minimum requirements

of American National Standard for Information Sciences – Permanence

of Paper for Printed Library Materials, ansi z39.48-1984.

Library of Congress Cataloging-in-Publication Data

Sverker Johansson

Origins of Language : Constraints on hypotheses / Sverker Johansson.

p. cm. (Converging Evidence in Language and Communication

Research, issn 1566–7774 ; v. 5)

Includes bibliographical references and index.

1. Language and languages--Origin. 2. Human evolution. 3.

Biolinguistics.

P116.O76

2005

401--dc22

2004066031

isbn 90 272 3891 X (Eur.) / 1 58811 629 8 (US) (Hb; alk. paper)

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John Benjamins Publishing Co. · P.O. Box 36224 · 1020 me Amsterdam · The Netherlands

John Benjamins North America · P.O. Box 27519 · Philadelphia pa 19118-0519 · usa

C HAPTER 10

WHY DID LANGUAGE EVOLVE?

In order to understand the evolution of language, we must advance our under-

standing of the purpose of language, and ‘purpose’ in an evolutionary context is

synonymous with selective advantage (Ganger & Stromswold, 1998). Different

hypotheses concerning the original selective advantage that drove the evolution of

language will be discussed in this chapter.

Evolution of complex and specialized features does not occur without being

driven by some selective pressure — some evolutionary advantage accruing to

those who possess the feature. As discussed in Section 9.3, it is well established

that language is such a complex and specialized feature (Pinker & Bloom, 1990).

But what was the crucial advantage conferred by language, that drove its evolu-

tion? One may think that the advantages of having a language are obvious — as

Lieberman (2003a) points out “it is difﬁcult to identify any aspect of human be-

havior (...) that would not proﬁt from [...] language, ...” (p. 670) — but that would

instead raise the question of why only humans have acquired it, why not a lot of

other animals as well, if it is so useful?

Szathmary (2001) identiﬁes two possible explanations for the uniqueness of an

apparently useful feature, such as language:

1. Variation-limited: The requisite combination of mutations has a very low prob-

ability of occurring.

2. Selection-limited: The feature will bring a selective advantage only under very

rare circumstances.

The ﬁrst possibility is in principle conceivable in the case of language, but it would

mean that the appearance of language in the human lineage, rather than that of

chimps or cockroaches, is a matter of pure chance. In that case, the problem of

language origins is not amenable to analysis, and not very interesting in any case

(though Szathmary (2001) calls the possibility ‘amusing’). The miraculous salta-

tionist models of language origins formerly favored by e.g., Chomsky (1988) and

Bickerton (1990), discussed in Section 9.5, belong in this category.

The second possibility is more interesting, and does appear more plausible, as

humans have many other unusual features, that may provide the unique circum-

194 Origins of language

stances that would favor language emergence. In that case, the problem at hand

is to identify whatever it was in human history, that made language particularly

advantageous for our ancestors, but not for the other apes. This has close parallels

with hypotheses concerning why our brains are so much larger, discussed in Sec-

tion 5.3.1. The different levels of evolution, as well as the features and limitations

of evolutionary processes, reviewed in Chapter 3, should also be kept in mind.

A particularly common pitfall here is the teleological scenario — that our an-

cestors evolved language because they needed it for some purpose or other. Future

utility of a trait is never valid as an explanation for its evolution, as this entails

backwards causation. Tenable hypotheses must be structured around selection

scenarios, instead — why did people with incipient stages of language have a

reproductive advantage over people without?

The issues raised in Section 6.3 must also be considered — the selective ad-

vantage of language must actually beneﬁt the spread of the speaker’s genes, not

just the general welfare of the group. Hypotheses of language evolution cannot be

based exclusively on how information recipients beneﬁt from language, without

explaining how that beneﬁt spreads back to the speaker.

Another important aspect, related to the previous points, is the context in which

language evolved. Before the advent of agriculture (which certainly postdates lan-

guage), humans lived as hunter-gatherers, in modest-sized tribes, presumably with

a lifestyle and social structure not vastly different from that of the few remaining

present-day hunter-gatherers. The chimpanzee lifestyle can reasonably be called

hunter-gatherer as well, though it is quite different from that of human hunter-

gatherers. Thus it appears not unreasonable to assume that language evolved in

a hunter-gatherer context, in tribes with a social structure somewhere in between

that of chimps and modern hunter-gatherers. This would be the ‘Environment of

Evolutionary Adaptedness’ (EEA), the Stone Age environment for which evolu-

tion has shaped us — the time since we abandoned the hunter-gatherer lifestyle is

much too short for any substantial evolutionary changes (Daly & Wilson, 1999;

Nesse & Williams, 1994; Byrne, 2000, but see also Irons (1998)). Reasonable hy-

potheses of language evolution must postulate that language carried some crucial

advantage for people in such an EEA society — advantages that language confers

only in modern industrialized (or even farming) societies are irrelevant.

Numerous hypotheses have been proposed as answers to these questions about

human language evolution, a selection of which will be evaluated here. In order

to provide some structure and overview, the hypotheses will be classiﬁed under

several categories, though the boundaries between the categories are sometimes

ﬂuid.

Why did language evolve? 195

10.1 Hunting

An obvious starting point is to postulate that language evolved for the purpose of

communication, and that the main selective advantage gained by improved com-

munication was enhanced coordination of group activities. Prominent among the

group activities discussed in this context is hunting, which has played a central

role in many scenarios for human evolution (Landau, 1991; Sagan, 1977), but

more general resource acquisition activities can be included here as well (Cziko,

1995). Apart from communication during hunts, the hunting argument has also

been connected with the teaching argument of Section 10.4 below:

The ‘quality education’ needed to become an expert Pleistocene hunter could not

do without a complex form of information transmittal interaction in which the tran-

scendence of the here and now, [...] played a key role. (Roebroeks, 2001, p. 451,

emphasis in original).

Hunting-related communication could be a signiﬁcant force in our evolution, only

if hunting was actually of major importance for our subsistence. Contrary to this,

it is commonly asserted that most hunter-gatherers, at least in the tropical areas

relevant to early human evolution (Ragir, 2000), don’t get nearly as much food

from hunting as from gathering. Kaplan et al. (2000), however, contest this claim,

and review a number of studies of actual calories hunted and gathered by members

of various tribes — on average, an adult hunter produces twice as many calories

per day as an adult gatherer. Kaplan et al. (2000) furthermore trace the ‘common

knowledge’ that hunting is unimportant back to a single study of questionable

generality (Lee, 1979, cited in Kaplan et al. (2000)).

The Inuit, who live in an Arctic environment with little plant food to gather,

incontrovertibly get most of their food from hunting, and very likely so did the

Neanderthals of Ice Age Europe, for similar reasons. Isotopic evidence from Ne-

anderthal fossils indicates that meat from large herbivores was a major part of their

diet, which implies that hunting was an economically vital activity (Richards et al.,

2000; Bocherens et al., 2001). But living in a glacial environment is a very late

development in human history, well after H sapiens and Neanderthals had gone

their separate ways, so an Arctic origin of language does not appear plausible.

Nevertheless, with the evidence presented by Kaplan et al. (2000) it would ap-

pear that hunting is highly signiﬁcant for modern human hunter-gatherers, and by

implication has been important for at least the later part of our evolution, so that a

role for hunting in the evolution of language is not excluded on these grounds.

There are, however, a few problems with the notion that hunter coordination

was a major driving force in language evolution. To begin with, modern humans

do not use all that much language during a hunt — it is a rather silent activity

(Dunbar, 2003b).

Furthermore non-human social carnivores manage to coordinate their collabo-

rative hunts without using language (Brinck & Gardenfors, 2003). This of course

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